From backing dimensions to a copyable cut list
For a rectangular paper-print frame with one uniform, flat moulding profile and 45° corners. Use the outside size of the backing or glazing, including any mat.
Worked example: 8 × 10 inch backing, 1.5 inch moulding, 0.25 inch rabbet overlap, 0.125 inch total clearance and 10% extra material.
Your four-rail cut list
Lengths are finished measurements between the two points on the same edge. Both ends are 45° mitres.
| Rails | Long point | Short point |
|---|---|---|
| 2 × top/bottom | 10.625 | 7.625 |
| 2 × sides | 12.625 | 9.625 |
Rail blanks total: 46.5 in. With your 10% extra: 51.15 in (4.2625 linear ft). Extra material: 4.65 in.
This is a length budget, not a stock-length cutting layout. Allow for saw kerf, end trimming, defects and your supplier’s stock lengths. The editable percentage does not guarantee enough material.
- Outside frame: 10.625 × 12.625 in
- Rabbet seating opening: 8.125 × 10.125 in
- Visible opening: 7.625 × 9.625 in
Front view, to scale. Dashed line: hidden rabbet seating edge. Diagram is not a cutting template. Check the actual profile, fit and measurements before cutting.
Measurements stay on this page and are not saved. Usage analytics count views, starts, completions, errors and link clicks without your measurements.
Browse custom portrait styles →Measure the rabbet width before calculating your rails
A traditional picture frame has a lip that overlaps the glazing or backing. The groove behind it is the rabbet, also called a rebate. Measure that overlap horizontally. The vertical depth of the groove answers a different question: whether your glazing, print, mat and backing stack will fit.
Enter the full moulding width from the outside edge to the visible opening, including the lip. The calculator subtracts the rabbet overlap when finding the outside dimensions. Measuring only the visible strip beside the glazing would count the overlap incorrectly.
If your print has a mat, use the outside mat or glazing size as the starting rectangle. Work out the window and borders first with the mat size calculator.
How the 45° rail calculation works
For each dimension, seating opening = backing size + total fitting clearance. Short-point length = seating opening − twice the rabbet overlap. Long-point length = short-point length + twice the full moulding width. Two width rails and two height rails form the rectangle.
For the 8 × 10 inch example above, a 1.5 inch moulding, 0.25 inch overlap and 0.125 inch total clearance give two 10.625 inch rails and two 12.625 inch rails measured along their outside edges. Their short points are 7.625 and 9.625 inches. The four long-point lengths add up to 46.5 inches before extra material.
The Professional Picture Framers Association study guide treats fitting allowance and saw-cut waste as separate parts of framing calculations. Here the clearance changes the fitted opening; your extra-material percentage changes only the length budget. Confirm both against your actual materials and cutting setup.
Use the length budget when planning your material purchase
The sum of the four long-point lengths is a baseline for four rail blanks. The editable extra percentage adds a reserve. It does not arrange the rails on stock lengths, model saw kerf or account for defects, decorative pattern matching or end trimming. Four short offcuts cannot replace one continuous rail.
This flat-profile calculation does not check joint strength, glazing thickness or mounting hardware. It also does not size a floating canvas frame. For stretched canvas, use the canvas floater frame calculator. For the finished piece on your wall, use the picture hanging height calculator.
How it works
- Choose inches or centimetres. Enter the outside backing or glazing width and height, including any mat. Use decimals, such as 0.25 for a quarter inch.
- Measure the full moulding width and horizontal rabbet overlap. Set the total fitting clearance added once to each dimension, then choose an extra-material percentage.
- Calculate and copy the four-rail cut list. Check the long-point and short-point labels against your frame profile and confirm your cutting layout before buying or cutting moulding.
Frequently asked questions
How much moulding do I need for an 8 × 10 picture frame?
With an 8 × 10 inch backing, 1.5 inch full moulding width, 0.25 inch rabbet overlap and 0.125 inch total clearance, the four long-point lengths total 46.5 inches. An editable 10% extra brings the budget to 51.15 inches. Your stock lengths and cutting losses may require more.
Do I measure rail length from the long points or short points?
The cut list gives both. Long points are the two outside corners of a rail; short points are the two corners at the visible opening. Measure along the same edge from point to point. For this flat 45° profile, the difference is twice the full moulding width.
Is rabbet width the same as rabbet depth?
No. This tool needs the horizontal overlap width of the lip that holds the backing. Rabbet depth runs from front to back and determines whether the glazing, artwork, mat and backing stack can fit. Check that depth separately.
Is the fitting clearance added to every side?
No. The entered clearance is added once to the width and once to the height. When centred, each side gets half of that amount. The 0.125 inch default is an editable example; choose the allowance appropriate to your materials and framer’s specifications.
Does this tell me how many lengths of moulding to buy?
It gives a total length budget, not an optimized stock layout or a stick count. Check that each rail fits within a continuous stock length, with enough room for saw cuts, trimming, defects and any pattern matching. The extra percentage is not a guarantee.
Can I use this for a canvas floater frame or wall panelling?
This calculator models a traditional rectangular frame with a rabbet overlapping a paper print’s backing or glazing. Floater frames have different support and reveal geometry, and wall panelling is a separate layout task. Use the dedicated canvas floater frame tool for canvas fit.
Is this free, and are my measurements uploaded or saved?
The calculator, diagram and copyable cut list are free with no signup or upload. Measurements remain in this page’s memory. They are not saved, sent in analytics or added to the optional portrait-browsing link. Usage analytics record fixed event categories only.
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